Heat exchanger

ABSTRACT

A heat exchanger for cooling a battery and/or an electronic component, having a first plate element and a second plate element. The two plate elements each have their main extension directions along a plane spanned by two spatial directions, and a wall thickness along the third spatial direction is much smaller. The two plate elements are stacked on top of each other and at least one flow channel is provided between the two plate elements. The first plate element has a greater extension than the second plate element in the plane of the main extension directions. A projection over the second plate element is formed. The plate elements are soldered to each other along an edge region of the second plate element. The solder extends beyond the solder surface between the plate elements in the direction of the projection and in the direction of the center of the heat exchanger.

This nonprovisional application claims priority under 35 U.S.C. §119(a) to German Patent Application No. 10 2014 110 459.5, which was filed in Germany on Jul. 24, 2014, and which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger, in particular for cooling a battery and/or an electronic component, comprising a first plate element and a second plate element, wherein the two plate elements have their main extension directions along a plane spanned by two spatial directions, and the wall thickness along the third spatial direction is much smaller, wherein the two plate elements are stacked on top of each other, and at least one flow channel is formed between the two plate elements.

2. Description of the Background Art

Heat exchangers, which have flow channels through which a coolant flows, are used to cool batteries and/or electronic components. The components to be cooled may be connected to the outer surfaces which delimit the flow channels. The heat may thus be easily discharged from the batteries or the electronic components.

EP 1 231 447 A2, which corresponds to U.S. Pat. No. 6,341,649, shows a plate-type heat exchanger, a flow channel, through which a coolant flows, being provided between two adjacent plate elements. One of the plate elements has a trough-shaped design, while the other plate element has a planar design. The planar plate element forms a C-shaped receiving area in its edge regions, in which the edge regions of the trough-shaped plate elements are accommodated. The plate elements are soldered to each other at the joints between the two plate elements, which are disposed adjacent to each other.

DE 197 50 748 A1, which corresponds to U.S. Pat. No. 6,182,746, which is incorporated herein by reference, and which shows a plate-type heat exchanger, which is formed from a plurality of trough-shaped plate elements which are stacked on top of each other. The upright edge regions of the individual plate elements are in contact with each other in the plate stack and are coated with a solder material. A permanently connected plate stack is produced by heating the plate stack to a temperature above the melting temperature of the solder.

U.S. 2011/0192576 A1 shows a vapor chamber which is formed by two plate elements. One plate element has a trough-shaped design and rests on a planar plate element with sections of the upright edge region running parallel to its base region. The edges of the planar plate element are bent upward and encompass the sections resting on the planar element in a C-shaped manner. A solder material is applied to the contact points between the two plate elements, which is melted on by the supply of heat in order to permanently connect the two plate elements to each other. A force component, which produces a stronger contact between the two plate elements and thus further improves the quality of the connection, is mounted in the regions bent in the shape of a C prior to the soldering process.

The disadvantage of the prior-art devices is, in particular, that in addition to a soldering process, mechanical deformations must also take place to generate a fluid-tight connection between the adjacent plate elements. In the case of a heat exchanger comprising a stack of trough-shaped plate elements, it is disadvantageous that a direct connection of components to be cooled to the outer surfaces of the heat exchanger is not possible.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a heat exchanger which has a simple structure and has a durable solder joint between the individual plate element, and components to be cooled being connectable to the outer surfaces of the flow channel.

An exemplary embodiment of the invention relates to a heat exchanger, in particular for cooling a battery and/or an electronic component, comprising a first plate element and comprising a second plate element, wherein the two plate elements each have their main extension directions along a plane spanned by two spatial directions, and the wall thickness along the third spatial direction is much smaller, wherein the two plate elements are stacked on top of each other and at least one flow channel is provided between the two plate elements, wherein the first plate element has a greater extension than the second plate element in the plane of the main extension directions, whereby a projection over the second plate element is formed, wherein the plate elements are soldered to each other along the edge region of the second plate element, and the solder extends beyond the solder surface, between the plate elements, in the direction of the projection as well as in the direction of the center of the heat exchanger.

The plate elements can be formed by metal bodies having an extension along a plane which is much larger than the extension in the third spatial direction, which is situated as the normal on the spanned plane. The wall thickness of the plate elements is measured along this third spatial direction.

Producing a projection of one plate element over the second plate element may achieve the fact that the solder distributed on the contact surface between the two plate elements is also able to flow out of the solder gap and is able to form a solder meniscus which surrounds the narrow side of the smaller plate element and thus generates an additional fixing of the plate elements against each other. If the two plate elements have a flush termination, this option is not possible, since the solder flowing out of the solder gap is unable to flow along the projection.

The projection can be provided along the entire edge region of the plate elements, so that the particular smaller plate element may be engaged by a solder meniscus in all four directions of the plane of the main extension directions.

An integral and form-locked fixing is generated by the engagement of the narrow side. The solder which extends in the direction of the center of the heat exchanger also forms a solder meniscus, which has a greater extension along the third spatial direction than the solder on the contact surface, so that a form-locked and integral fixing of the plate elements with respect to each other is also generated on this side of the solder joint.

A solder meniscus is understood to be the portion of the solder which exits the solder gap on the edge side and forms a region which has a greater extension, in particular along the third spatial direction, than the solder which is distributed within the solder gap.

In an embodiment, the solder on the side of the projection can engage with the second plate element along its narrow side forming the wall thickness. The engagement of the narrow side, generated by the outflow of the solder from the solder gap toward the side of the projection, is advantageous to increase the stability of the solder joint. In particular, a relative shifting of the plate elements with respect to each other is thereby effectively avoided or made more difficult.

The solder, which extends beyond the solder surface on the side of the center of the heat exchanger, can extend into the provided flow channel, the extension of the solder along the third spatial direction increasing in the direction of the center of the heat exchanger.

Due to the formation of a solder meniscus on the side facing the center of the heat exchanger, the quality of the solder joint may be significantly increased, in particular with regard to its durability. Since the two plate elements at least partially lift away from each other, due to the formation of the flow channel, a hopper-like cross-section is provided, starting from the solder surface, into which the solder may flow and thus form a solder meniscus.

The second plate element can be fixed with respect to the first plate element in a form-locked and integral manner along the plane of the main extension directions, due to the solder on the side of the projection and the solder on the side of the center of the heat exchanger.

The formation of at least one solder meniscus on the side facing the projection and on the side of the solder surface facing the center of the heat exchanger may avoid or minimize, in particular, a relative movement of the plate elements with respect to each other in the direction of the spatial directions which form the plane of the main extension directions of the plate elements and counter to these directions.

It is also advantageous if one of the plate elements has a recess which is covered by the other plate element, the contact surface between the two plate elements being reduced in size by the cross-sectional area of the recess.

A recess is advantageous to reduce the size of the contact surface between the two plate elements in a targeted manner. This is advantageous, in particular, to obtain additional edges or shoulders running transversely to the solder surface, which may be at least partially engaged by the solder. In the case of a closed contact surface which is not interrupted by a recess, a solder meniscus may form only on the outwardly oriented edges of the solder surface. By providing the recess, a solder meniscus may additionally form, which is oriented toward the center of the recess and which facilitates an additional fixing of the plate elements relative to each other. The reduction of the contact surface or the solder surface by the recess is thus offset by the positive effect of the additional solder meniscus. It is advantageous if the recess is dimensioned in such a way that the stability loss of the solder joint, due to the reduced contact surface, is smaller than the increase in stability due to the additional solder meniscus.

The shorter length of the contact surface, which results between the plate elements without the provision of a recess, can be at least greater than the double wall thickness of the thicker plate element, the shorter length of the contact surface being measured along the plane of the main extension directions.

It is advantageous to provide a recess for interrupting the contact surface if the shorter length of the contact surface or the solder surface produced in the case of a joint is at least greater than the double wall thickness of the thicker plate element. The definitive length of the contact surface or the solder surface is measured along the plane, along which the main extension directions of the plate elements lie. The particular wall thickness of the plate elements is measured along the spatial direction which is situated as the normal on the plane. A ratio of this type is advantageous to avoid any disadvantageous effects on the durability of the solder joint due to the reduction in size of the contact surface.

The particular thicker plate element can have the recess. This is particularly advantageous to avoid significantly negatively influencing the stability of the heat exchanger by providing the recess.

The plate element can have the recess soldered to the particular other plate element along the edge of the recess, the narrow side extending along the third spatial direction being engaged by a solder region, and another solder region extending beyond the solder surface in the direction of the flow channels, the solder region along the third spatial direction having a greater extension than the solder surface.

By soldering along the edge of the recess, it is possible to achieve the fact that the solder extends into the recess along the particular plate element not interrupted by a recess in the region of the contact surface and thus at least partially engages the narrow side or the wall delimiting the recess in the radial direction, in order to generate an additional fixing of the plate elements with respect to each other. As when soldering along the edge region of the two plate elements, the solder also flows out of the solder surface, oriented away from the recess, and along the two plate elements in this location, whereby a solder meniscus is also formed, which is used to fix the plate elements to each other.

It is also expedient if a single flow channel or a plurality of flow channels is provided between the two plate elements, each flow channel being formed from the plane of the main extension directions by a trough-shaped region of at least one plate element . The trough-shaped regions may be embossed into the otherwise planarly designed plate element by means of an embossing method. The particular flow channels are each limited by the contact of the two plate elements.

In an embodiment, it may also be provided that the two plate elements each can have trough-shaped regions which together form a flow channel or alternately form a flow channel extending into the one plate element and a flow channel extending into the particular other plate element. The flow channels may be advantageously connected to each other by overflow sections or they may be connected to feed lines and/or discharge lines by fluid connections.

In addition, a third planar plate element can be disposed on the side of the plate element which has the trough-shaped region and faces away from the flow channel, the third plate element having a greater extension in the plane of the main extension directions than the plate element which has the trough-shaped region, whereby the third plate element forms a projection thereover.

An additional third plate element can create a planar connecting surface for the components to be cooled. In particular, the plate element which has the trough-shaped region does not have a planar connecting surface toward the outside, whereby, on the one hand, the connection is made more difficult and, on the other hand, the heat transfer is made worse. In an embodiment, an additional planar plate element may also be connected to the two plate elements, for example if neither of the two original plate elements has a planar outer surface.

The third plate element can be soldered to the plate element which has the trough-shaped region, the solder extending beyond the contact surface between the two elements in the direction of the edge region of the third plate element, and the plate element which has the trough-shaped region engaging along the third spatial direction.

A projection can be provided between the third plate element and the plate element to which it is connected in order to facilitate the outflow of the solder from the contact region or the solder surface and to facilitate an engagement of the particular narrow side. This increases the stability and the durability of the solder joint.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

FIG. 1 shows a cross section of a heat exchanger, as known from the prior art, the two plate elements forming the heat exchanger being shown at a distance from each other;

FIG. 2 shows a cross section of a heat exchanger according to FIG. 1, the two plate elements being mounted on each other;

FIG. 3 shows a cross section of a heat exchanger according to FIGS. 1 and 2, the solder layer between the two plate elements being illustrated;

FIG. 4 shows a cross section of two plate elements of a heat exchanger, one plate element extending beyond the other plate element on the edge side and forming a projection;

FIG. 5 shows a cross section of a heat exchanger according to FIG. 4, a solder layer which forms a solder meniscus on both ends of the solder layer being shown between the two plate elements;

FIG. 6 shows a cross section of a heat exchanger comprising two flow channels, the two plate elements being soldered to each other along a contact surface;

FIG. 7 shows a cross section of a heat exchanger, one of the plate elements having a recess in the region of the contact surface;

FIG. 8 shows a cross section of a heat exchanger, nub-like elements being provided in the flow channel, and an additional planar plate element being connected to the plate element which has the trough-shaped regions; and

FIG. 9 shows a cross section of a heat exchanger according to FIG. 8, the solder between the individual plate elements being illustrated.

DETAILED DESCRIPTION

FIGS. 1 through 3 each show a heat exchanger 12 or the two plate elements 1, 2 from which heat exchanger 12 is formed. Heat exchanger 12 is a heat exchanger which is already known from the prior art.

FIGS. 1 through 9 below are each based on the coordinate system shown in FIG. 1, which includes three spatial directions 6, 7 and 8. The two spatial directions 6 and 7 form a plane, along which the illustrated plate elements each have their main extension. In each case, the wall thickness of the individual plate elements is measured along third spatial direction 8 of the coordinate system.

FIG. 1 shows a sectional view of a planar plate element 1 and a plate element 2 disposed thereunder, which has a trough-shaped region 3. Trough-shaped region 3 is formed from planar region 4 using an embossing method or a similar method. Due to trough-shaped region 3, a cavity 5 results, which may be closed off to form a flow channel 5 by mounting upper plate element 1. Components to be cooled, such as batteries or electronic components, may be connected to the upward oriented outer surface of plate element 1 as well as to the downward oriented outer surface of plate element 2 and, in particular, to trough-shaped region 3. A coolant or refrigerant may flow through flow channel 5, which is not completely provided in FIG. 1, whereby a cooling of the components connected on the outside may be achieved.

FIG. 2 shows a sectional view of heat exchanger 12, upper plate element 1 being mounted on planar region 4 of lower plate element 2. A contact surface 9 is formed in the region of planar region 4 between first plate element 1 and second plate element 2.

Contact surface 9 advantageously runs completely all around and along the edge region of plate element 1, whereby a closed flow channel 5 is produced between plate elements 1, 2.

FIG. 3 shows another sectional view of heat exchanger 12, a solder surface 10 being provided between first plate element 1 and second plate element 2. The solder surface is provided, in particular, between planar region 4 and first plate element 1 in the region which is described by contact surface 9 in FIG. 2. A solder region 11, which has an increasing extension along third spatial direction 8, is illustrated in the right end region of solder surface 10. The extension of solder region 11 is delimited, in particular, by the beginning of trough-shaped region 3 and thus by the distance of plate element 2 from the lower surface of plate element 1.

Plate elements 1 and 2 of heat exchanger 12 in FIGS. 1 through 3 lie flush against each other, in particular, in their left-oriented edge region. This means, in particular, that no projection of one of plate elements 1, 2 over the other one is produced. This results in that the solder which is disposed between plate elements 1, 2, in particular on the left-oriented end region, is distributed only between plate elements 1, 2 and engages none of plate elements 1, 2 on the end in such a way that a fixing along spatial direction 6 or spatial direction 7 is produced. In the exemplary embodiment in FIGS. 1 through 3, only the solder meniscus designated by solder region 11 is provided.

FIG. 4 shows a heat exchanger 31 according to the invention. Heat exchanger 31 has a planar plate element 20 and a second planar element 21, which has a downwardly formed, trough-shaped region 23, which forms a flow channel 22 between first plate element 20 and second plate element 21.

In contrast to the preceding FIGS. 1 through 3, upper plate element 20 is designed in such a way that it has a greater extension than lower plate element 21 in the plane formed by main extension directions 6 and 7. This produces a projection 26, which extends, in particular, beyond the edge region of lower plate element 21 along spatial direction 6. A contact surface 25 is formed between plate element 20 and plate element 21, in particular along planar region 24.

In a heat exchanger 31, as illustrated in FIG. 4, projection 26 is provided all around and along the entire edge region of the heat exchanger. This means that upper plate element 20 has the projection 26 over the lower plate element 21 along the entire plane spanned by spatial directions 6 and 7. Alternatively, the trough-shaped plate element may also have a greater extension than lower plate element 21.

FIG. 5 shows a representation of heat exchanger 31 according to FIG. 4, solder surface 27, which forms, in particular, a solder region 28 and a solder region 30 at the edges of solder surface 27, being shown between upper plate element 20 and lower plate element 21.

Solder region 28, which forms an additional solder meniscus, is designed in such a way that it protrudes over the edge of plate element 21 along projection 26, and engages with plate element 21 on its narrow side 29 extending along third spatial direction 8. In addition, solder region 30 forms a solder meniscus similar to solder region 11 shown in FIG. 3. Due to the two solder regions 28, 30, plate element 21 is fixed in a form-locked and integral manner along spatial direction 6 as well as counter to spatial direction 6. This increases the connection quality between plate elements 20 and 21.

Solder region 28 may be provided, in particular, on the basis of projection 26, since, during processing, the solder from solder surface 27 is able to exit the gap between plate elements 20, 21 on the downward-oriented surface of plate element 20 and may thus form a solder meniscus 28, which engages with narrow side 29 of lower plate element 21.

Since solder surface 27 is provided all around and along the edge region of plate elements 20 and 21, a fixing of plate elements 20, 21 along spatial directions 6 and 7 as well as counter to spatial directions 6 and 7 is produced by solder region 30 and, in particular, solder region 28. This is particularly advantageous, in particular with regard to a durable solder joint between plate elements 20, 21 and offers a much better quality compared to the prior art illustrated in FIGS. 1 through 3.

FIG. 6 shows a sectional view of a heat exchanger 41. In the detail in FIG. 6, two flow channels 43 are each formed by trough-shaped regions 44 in lower plate element 42 between upper planar plate element 40 and lower plate element 42. Solder surface 45 is formed along planar region 48 between plate elements 40 and 42. The illustration in FIG. 6 shows the prior art. Solder regions 46, each of which forms a solder meniscus, are provided to the left and right of the end regions of solder surface 45.

FIG. 7 shows a sectional view of a heat exchanger 51 according to the invention, upper planar plate element 50 having a recess 52. Recess 52 is provided, in particular, in the region of planar region 55 of lower plate element 53. Lower plate element 53 has two downwardly oriented, trough-shaped regions 54, which form flow channels 56 between plate element 50 and plate element 53.

Plate element 50 is in contact with planar region 55 on the two edge regions of planar region 55 facing flow channels 56.

Solder surfaces 57 are provided in this contact region. Each of contact surfaces 57 has one solder region oriented toward recess 52 as well as one solder region 59 oriented toward flow channel 56. Each of solder regions 58 and 59 forms one solder meniscus, solder menisci 58 each engaging with upper plate element 50 along spatial direction 8, and solder menisci 59 each engaging with lower plate element 53 along spatial direction 8.

A support for upper late element 50 with respect to lower plate element 53 is provided in this way in both a form-locked and integral manner. Although solder surfaces 57 are, as a whole, smaller than solder surfaces 45 shown in FIG. 6, as illustrated in FIG. 7, a durable solder joint between plate elements 50, 53 is, however, produced by the additional formation of solder menisci 58. Recess 52 illustrated in FIG. 7 may be produced, for example, by a perforation or a boring operation.

A provision of a recess 52, as illustrated in FIG. 7, is advantageous, in particular, if the solder surface between plate elements 50 and 53 has at least one extension along the plane of spatial directions 6 and 7 which is at least twice the size of the wall thickness of one of the two plate elements 50 or 53, measured along spatial direction 8.

FIG. 8 shows a sectional view of a heat exchanger 70. As described above, heat exchanger 70 is formed by a planar plate element 71 and a second plate element 72, which has a downwardly oriented, trough-shaped region 84. A flow channel 76 is provided between plate element 71 and plate element 72. Plate element 72 furthermore has a nub-like structure 75 on its downwardly-oriented, trough-shaped region 84, which may be formed from plate element 72, for example using an embossing method. Nub-like elements 75 extend into flow channel 76 and are in contact with the downward-facing surface of upper plate element 71. Due to nub-like elements 75, a turbulent flow may be generated within flow channel 76, and the flow may be further influenced, in particular in its flow direction.

By embossing nub-like elements 75 from plate element 72, the downwardly oriented surface of plate element 72, in particular, is interrupted, whereby the connection of components to be cooled to lower plate element 72 is made more difficult. Therefore, a third plate element 73 is provided in heat exchanger 70 in FIG. 8, which, like plate element 71, also has a planar design and is connected to the downwardly oriented surface of plate element 72. A solder joint is also produced between plate element 72 and lower plate element 73.

As in the preceding FIGS. 4 through 7, upper plate element 71 has a projection 78 over middle plate element 72. In addition, lower plate element 73 has a projection 77, provided along spatial directions 6 and 7, over downwardly oriented surface, which is formed by trough-shaped region 84 of plate element 72.

FIG. 9 shows another view of heat exchanger 70, solder surface 81 and solder surface 82, including their corresponding solder regions 79 and 80, being illustrated in FIG. 9.

Solder surface 81 is provided between upper plate element 71 and middle plate element 72. The solder surface is designed, in particular, similarly to FIG. 5. Solder region 79, in particular, is illustrated in FIG. 9, which shows the solder meniscus which is formed outwardly toward projection 78 and which engages with plate element 72 on its narrow side 83.

Solder surface 82 between plate element 72 and plate element 73 is additionally illustrated, which, on the basis of projection 77, forms a solder region 80 or solder meniscus 80, which at least partially engages with middle plate element 72, in particular in the direction of third spatial direction 8.

Due to additional plate element 73, battery cells or entire batteries or electronic components may be easily connected to heat exchanger 70, in particular also in a downward manner. Projection 77 of plate element 73 is advantageous, in particular, to produce an additional engagement of middle plate element 72 by solder region 80.

The individual features of the preceding FIGS. 4, 5 and 7 through 9 may also be combined with each other. They are not limiting in nature, in particular with regard to their geometric design, material selection and dimensioning of the individual elements. In particular, planar plate elements 20, 40, 50 and 71 may have a greater wall thickness than plate elements 21, 42, 53 and 72, which have trough-shaped regions 23, 44, 54 and 82. Third plate element 73, which is disposed on the bottom in FIGS. 8 and 9, may also have a greater wall thickness, which corresponds to the wall thickness of upper plate elements 20, 40, 50 and 71.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims. 

What is claimed is:
 1. A heat exchanger comprising: a first plate element; a second plate element, the first and second plate elements each having their main extension directions along a plane spanned by two spatial directions and a wall thickness along a third spatial direction being smaller, the first and second plate elements being stacked on top of each other; at least one flow channel formed between the first and second plate elements; and a projection provided over the second plate element, wherein the first plate element has a greater extension than the second plate element in the plane of the main extension directions, wherein the first and second plate elements are soldered to each other along an edge region of the second plate element, the solder extending beyond a solder surface between the first and second plate elements in a direction of the projection as well as in a direction of a center of the heat exchanger.
 2. The heat exchanger according to claim 1, wherein the solder surrounds the second plate element along a narrow side forming the wall thickness on the side of the projection.
 3. The heat exchanger according to claim 1, wherein the solder, which extends beyond the solder surface on the side of the center of the heat exchanger, extends into the flow channel, and wherein the extension of the solder along the third spatial direction increases in the direction of the center of the heat exchanger.
 4. The heat exchanger according to claim 1, wherein the second plate element is fixed against the first plate element in a form-locked and integral manner along a plane of the main extension direction due to the solder on the side of the projection and the solder on the side of the center of the heat exchanger.
 5. The heat exchanger according to claim 1, wherein one of the plate elements has a recess that is covered by the other plate element, wherein the contact surface between the two plate elements being reduced in size by the cross-sectional area of the recess.
 6. The heat exchanger according to claim 5, wherein a shorter length of the contact surface, which results between the two plate elements without the provision of a recess, is at least greater than a double wall thickness of the thicker plate element, the shorter length of the contact surface being measured along the plane of the main extension directions.
 7. The heat exchanger according to claim 5, wherein the thicker plate element has the recess.
 8. The heat exchanger according to claim 5, wherein the plate element having the recess is soldered to the particular other plate element along an edge of the recess, wherein the narrow side extending along the third spatial direction is engaged by a solder region, and another solder region extending beyond the solder surface in the direction of the flow channel, and wherein the solder region along the third spatial direction has a greater extension than the solder surface.
 9. The heat exchanger according to claim 1, wherein a single flow channel or a plurality of flow channels is provided between the two plate elements, each flow channel being formed from the plane of the main extension directions by a trough-shaped region of at least one plate element.
 10. The heat exchanger according to claim 9, wherein a third planar plate element is disposed on the side of the plate element which has the trough-shaped region and faces away from the flow channel, wherein the third plate element has a greater extension in the plane of the main extension directions than the plate element which has the trough-shaped region, and wherein the third plate element forms a projection thereover.
 11. The heat exchanger according to claim 10, wherein the third plate element is soldered to the plate element which has the trough-shaped region, the solder extending beyond the contact surface between the first and second plate elements in the direction of the edge region of the third plate element, and the plate element which has the trough-shaped region engages along the third spatial direction. 